用铁皮做一只无盖圆柱体的水桶，底面直径4分米，高4分米，做这只水桶要用铁皮多少平

已知圆C的方程为x²+y²+(m-2)x+(m+1)y+m-2=0，根据下列条件确定实数m的取值，并写出相应的圆心坐标和半径。

⑴圆的面积最小；

⑵圆心距离坐标原点最近。

下列何种化合物的生物合成途径为醋酸-丙二酸途径

A．甾体皂苷

B．三萜皂苷

C．生物碱类

D．葸醌类

E．木质素类

电视机中梳状滤波器的功能是从全色度电视信号中分离出（）

A．B-Y和R-Y两个色差信号

B．色度信号和干扰信号

C．G-Y和R-Y两个色差信号

D．亮度信号和两个色差信号

完成句子。

1. Even in New York you still can see many people ______ (穿得破烂).

2. Her parents died when she was a baby and she ______ (抚养) by her aunt.

3. It doesn't seem expensive to me; ______ (相反), I think it's rather cheap.

4. We ______ (打赌) on who's going to recite this text first.

5. ______ (无意中), I found the reason why the room can stay up after the terrible storm.

我国著名的青铜器作品《人面鼎》产生于______时期。

A．殷商

B．战国

C．东汉

D．西汉